JP2005109403A - Method for manufacturing laser module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a contaminant in a container for obtaining satisfactory characteristics and reliability in a laser module, where a semiconductor laser device is installed in the container. <P>SOLUTION: An adhesive composition is inserted between at least one optical component (for example, the semiconductor laser device 6) in the container 2 and a fixing member (for example, a submount 5) for fixing the optical component so that adhesion thickness becomes ≥0.05 μm and ≤5 μm before curing is made by an active energy ray for fixing the optical component 6 to the fixing member 5. In this case, the adhesive composition contains an alicyclic epoxy compound having an epoxy group, a compound having an oxetanyl group, and an onium salt photoreaction initiator for catalyst quantity. The container 2 is airtightly sealed after at least the container 2 and the semiconductor laser device 6 are irradiated with plasma. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a laser module in which a semiconductor laser element is installed in a container and hermetically sealed.

  Conventionally, a laser module in which a semiconductor laser element, a collimator lens, a condenser lens, an optical fiber, and the like are sealed in an airtight container is known. In this type of laser module, a problem has been recognized that contaminants remaining in the hermetically sealed container adhere to optical components such as the emission end face of the semiconductor laser element, lenses, and optical fibers, thereby degrading laser characteristics. Examples of the pollutants include hydrocarbon compounds mixed in from the atmosphere of the manufacturing process, and it is known that the hydrocarbon compounds are polymerized or decomposed by laser light and adhered.

  In order to solve this problem, various methods have been proposed as described below. For example, in Patent Document 1, it is effective to reduce the amount of hydrocarbon in the container to 0.1% or less in order to prevent a decrease in the output of laser light having a wavelength of 400 nm or less. It describes that deposition on parts and the like can be prevented. In addition, it has been proposed that the sealing atmosphere be dry air, and an effect of removing the deposit by a photochemical reaction between oxygen in the atmosphere and deposited hydrocarbon is expected.

  Further, in Patent Document 2, in order to prevent the adhesion of contaminants to the end face of the semiconductor laser element due to the photolysis of an organic gas such as hydrocarbon, 100 ppm or more of oxygen is sealed for the purpose of decomposing this gas. It is described that it is mixed with gas.

  Patent Document 3 describes that long-term reliability can be ensured by degreasing and washing away contaminants such as oil.

On the other hand, Patent Document 4 proposes a laser module using a GaN-based semiconductor laser element having an oscillation wavelength of 350 to 450 nm. However, in this type of laser module, a short wavelength laser beam has high energy. The hydrocarbon polymerized or decomposed in the module has a high probability of adhering to the end face of the semiconductor laser element or the optical component, which is a particular problem.
Japanese Patent Laid-Open No. 11-167132 U.S. Pat.No. 5,392,305 Japanese Patent Laid-Open No. 11-87814 Japanese Patent Laid-Open No. 2002-202442

The hydrocarbon-based deposit generated by the reaction between the laser beam and the hydrocarbon is decomposed into CO ₂ and H ₂ O in a gas atmosphere containing a certain amount or more of oxygen as shown in Patent Document 2 above. Is eliminated.

  However, in this type of deposit, not only hydrocarbons but also silicon compounds have been confirmed, and it has been found that the silicon compounds cannot be decomposed and removed only by containing oxygen in the atmosphere. Since the deposits of hydrocarbons and silicon compounds generate optical absorption, there is a problem that reliability over time in continuous oscillation is significantly impaired. The silicon compound to be deposited is a photochemical reaction between an organic compound gas containing Si such as a siloxane bond (Si—O—Si) or a silanol group (—Si—OH) (hereinafter referred to as an organosilicon compound) and laser light. And the presence of oxygen in the atmosphere has the effect of increasing the reaction rate. The term “silicon compound” as used herein refers to a compound having any structure including silicon, regardless of organic or inorganic, and includes inorganic SiOx and organic silicon compounds.

  The generation source is a gas emitted mainly from a silicone-based material used in an arbitrary place in the laser module manufacturing process. This may be adhered to the surface of each component in the laser module, and when the module is used in a sealed state, it is contained in a small amount in the sealing gas. In order to manage the gas components during the manufacturing process, it cannot be completely removed by installing a normal clean room or a sealed gas purifier, and a large capital investment is required. Further, even when the oil component or the like is degreased or washed as disclosed in Patent Document 3, it is unavoidable that the compound is mixed from the manufacturing process atmosphere. Since cleaning uses liquid organic substances, it is necessary to manage impurities in the drying process. In addition, it is necessary to select a cleaning agent that does not dissolve the adhesive used to fix the semiconductor laser element, optical member, etc. in the container, and this often contradicts the maintenance of the cleaning ability of organic substances adhering to the component surface. .

  Hydrocarbon compounds, silicon compounds and the like adhering to the components in the laser module can be removed by decomposition and evaporation by heat treatment at a temperature of 200 ° C. or higher, preferably 300 ° C. or higher. However, heat treatment requires several to several tens of hours of processing time, and when fixing the components in the module with an organic adhesive, the mechanical properties due to the thermal deterioration of the adhesive deteriorate, so this method should be used. I can't.

  In view of the above circumstances, the present invention provides a method capable of manufacturing a laser module in which a semiconductor laser element is disposed and hermetically sealed in a container as a highly reliable product from which contaminants in the container are well removed. The purpose is to provide.

A first laser module manufacturing method according to the present invention is a laser module manufacturing method in which a semiconductor laser element is installed in a container and hermetically sealed,
An alicyclic epoxy compound having an epoxy group, a compound having an oxetanyl group, and a catalytic amount of an onium salt photoinitiator are contained between at least one optical component in the container and a fixing member for fixing the optical component. After inserting the adhesive composition to be fixed, the optical component is fixed to the fixing member by curing with an active energy ray,
Before the container is hermetically sealed, at least the inside of the container and the semiconductor laser element are irradiated with plasma.

A second laser module manufacturing method according to the present invention includes a semiconductor laser element, an optical fiber, and an optical member for inputting laser light emitted from the semiconductor laser element into the optical fiber. Is a method of manufacturing a laser module for hermetically sealing
An alicyclic epoxy compound having an epoxy group, a compound having an oxetanyl group, and a catalytic amount of an onium salt photoinitiator are contained between at least one optical component in the container and a fixing member that fixes the optical component. After inserting the adhesive composition to be fixed, the optical component is fixed to the fixing member by curing with an active energy ray,
Before the container is hermetically sealed, at least the inside of the container, the semiconductor laser element, the optical fiber, and the optical member are irradiated with plasma.

  In the first and second laser module manufacturing methods according to the present invention, the adhesive composition inserted between the optical component and the fixing member for fixing the optical component has an adhesive thickness of 0.05 μm or more and 5 μm or less. It is desirable to insert so that

  Moreover, it is desirable that the gas sealed in the container is at least one of an inert gas, nitrogen, and oxygen.

  The oscillation wavelength of the semiconductor laser element is preferably 450 nm or less.

  The plasma irradiation is performed “before airtight sealing” as described above, but may be performed after the semiconductor laser element or the like is installed in the container, that is, in a state where each component is installed in the container, or You may carry out in the state of the parts before installing. Further, plasma irradiation may be performed in the state of the component, and plasma irradiation may be performed after the component is installed in the container.

  On the other hand, it is preferable that the adhesive composition contains a silane coupling agent.

  The adhesive composition preferably contains spherical silica particles having an average diameter of 0.1 μm or more and 1.0 μm or less.

  The fixing member is preferably made of a metal member, and the optical component is preferably made of an inorganic transparent member.

On the other hand, it is desirable that the compound having an oxetanyl group is represented by the following general formula (1).

In the formula (1), R ₁ represents a methyl group or an ethyl group, and R ₂ represents a hydrocarbon group having 6 to 12 carbon atoms.

  Furthermore, it is desirable to use an adhesive composition having a viscosity at room temperature of 10 mPa · s to 1,000 mPa · s and a contact angle with the adherend of 40 ° or less.

  The adhesive composition used in the present invention is also described in JP-A-2001-177166, but will be described in detail below.

  This adhesive composition contains an alicyclic epoxy compound having an epoxy group, a compound having an oxetanyl group, and a catalytic amount of an onium salt photoinitiator as essential components. These compounds and initiators may be either one kind or a mixture of two or more kinds.

  In the present invention, an epoxy compound having two or more epoxy groups in one molecule can be used. As the epoxy compound, two or more epoxy groups in one molecule and an alicyclic structure are provided. An alicyclic epoxy compound having two or more epoxy groups in one molecule is preferably used rather than a glycidyl compound that does not. “A cycloaliphatic epoxy compound having an epoxy group” means one molecule of a partial structure obtained by epoxidizing a cycloalkene ring double bond such as a cyclopentene group or a cyclohexene group with an appropriate oxidizing agent such as hydrogen peroxide or peracid. A compound having two or more in it. The alicyclic epoxy compound having an epoxy group of the present invention is preferably a compound having two or more cyclohexene oxide groups or cyclopentene oxide groups in one molecule. Specific examples of such alicyclic epoxy compounds include 4-vinylcyclohexylene dioxide, (3,4-epoxycyclohexyl) methyl-3,4-epoxycyclohexylcarboxylate, di (3,4-epoxycyclohexyl) adipate. , Di (3,4-epoxycyclohexylmethyl) adipate, bis (2,3-epoxycyclopentyl) ether, di (2,3-epoxy-6-methylcyclohexylmethyl) adipate, and dicyclopentadiene dioxide. One type of alicyclic epoxy compound having an epoxy group may be used, or a mixture of two or more types may be used. Various alicyclic epoxy compounds are commercially available and can be obtained from Union Carbide Japan Co., Ltd., Daicel Chemical Industries, Ltd., and the like.

  Further, a glycidyl compound having two or more epoxy groups in one molecule and having no alicyclic structure can be used in combination with the alicyclic epoxy compound in an amount of substantially equal to or less than the same weight. Examples of such glycidyl compounds include glycidyl ether compounds and glycidyl ester compounds, but it is preferable to use glycidyl ether compounds in combination. Specific examples of the glycidyl ether compound include 1,3-bis (2,3-epoxypropyloxy) benzene, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac. Glycidyl ether compounds such as epoxy resins, trisphenolmethane epoxy resins, aliphatic glycidyl ethers such as 1,4-butanediol glycidyl ether, glycerol triglycidyl ether, propylene glycol diglycidyl ether, and trimethylolpropane tritriglycidyl ether Compounds. Examples of the glycidyl ester include glycidyl ester of linolenic acid dimer. The glycidyl compound used in combination with the alicyclic epoxy compound may be one kind or a mixture of two or more kinds. Glycidyl ethers are commercially available from Yuka Shell Epoxy Co., Ltd.

  The compound having an oxetanyl group (hereinafter also simply referred to as “oxetane compound”) is a compound having one or more oxetanyl groups in one molecule. This oxetanyl group-containing compound is roughly classified into a compound having one oxetanyl group in one molecule and a compound having two or more oxetanyl groups in one molecule.

As the monofunctional oxetane compound having one oxetanyl group in one molecule, a compound represented by the following general formula (1) is preferable.

In the formula (1), R ₁ represents a methyl group or an ethyl group, and R ₂ represents a hydrocarbon group having 6 to 12 carbon atoms. The hydrocarbon group for R ₂ may be a phenyl group or a benzyl group, but is preferably an alkyl group having 6 to 8 carbon atoms, particularly preferably a branched alkyl group such as a 2-ethylhexyl group. Examples of oxetane compounds in which R ₂ is a phenyl group are described in JP-A-11-140279. An example of an oxetane compound which is a benzyl group in which R ₂ may be substituted is described in JP-A-6-16804. The oxetane compound in which R ₁ is an ethyl group and R ₂ is a 2-ethylhexyl group is preferably used in the present invention as an excellent diluent, curing accelerator, flexibility imparting agent, and surface tension reducing agent. .

In the present invention, a polyfunctional oxetane compound having two or more oxetanyl groups in one molecule can be used, but a preferred compound group is represented by the following general formula (2).

In formula (2), m represents a natural number of 2, 3 or 4, and Z represents an oxygen atom, a sulfur atom or a selenium atom. R ₃ is a hydrogen atom, a fluorine atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a fluoroalkyl having 1 to 6 carbon atoms, an allyl group, a phenyl group or a furyl group. R ₄ is an m-valent linking group, preferably a group having 1 to 20 carbon atoms, and may contain one or more oxygen atoms and sulfur atoms. Z is preferably an oxygen atom, R ₃ is preferably an ethyl group, m is preferably 2, and R ₄ is preferably a linear or branched alkylene group having 1 to 16 carbon atoms or a linear or branched poly (alkyleneoxy) group. Further preferred are compounds in which any two or more of the preferred examples for R ₃ , R ₄ , Z and m are combined.

  The onium salt photoinitiator used in the present invention refers to an onium salt that is considered to generate active chemical species by irradiating an adhesive composition with active energy rays. As the onium salt photoreaction initiator, aromatic iodonium salts, aromatic sulfonium salts and the like are preferable because they are thermally relatively stable. Here, the active energy ray is an energy ray that can generate a chemically active species (cationic species such as Lewis acid, Bronsted acid, etc.) that can act on an onium salt to initiate a chemical reaction, and is capable of producing ultraviolet rays, electron beams, and the like. , Gamma rays, X-rays and the like, but ultraviolet rays are preferably used.

When an aromatic sulfonium salt and an aromatic iodonium salt are used as an onium salt photoinitiator, the counter anions include BF ₄ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , PF ₆ ⁻ , PF ₆ ⁻ , B (C ₆ F ₅ ) _4- ^{and the} like. As the initiator, PF ₆ salt or SbF ₆ salt of aromatic sulfonium can be preferably used since it has solubility and moderate polymerization activity. In order to improve the solubility, one or more alkyl groups or alkoxy groups having 1 to 10 carbon atoms are introduced into the aromatic group, usually phenyl group, of the aromatic group iodonium salt or aromatic sulfonium salt. A chemical structure is preferred. PF ₆ salt or SbF ₆ salt of aromatic sulfonium salt is commercially available from Union Carbide Japan Co., Ltd. Asahi Denka Kogyo Co., Ltd. also sells PF ₆ salt of aromatic sulfonium under the trade name of Adekaoptomer SP series. The aromatic sulfonium salt has absorption up to about 360 nm, and the aromatic iodonium salt has absorption up to about 320 nm. Therefore, in order to cure the aromatic sulfonium salt, it is preferable to irradiate ultraviolet rays including spectral energy in this region.

Among the chemical structural formulas shown below, sulfonium salts PI-3 and PI-4 are preferably used because of their high light absorption efficiency.

  The onium salt photoinitiator used in the present invention generates an active cationic species by the action of an active energy ray, and cationically polymerizes an alicyclic epoxy compound and a compound having an oxetanyl group, whereby the adhesion of the present invention. It is considered to cure the adhesive composition.

  In the adhesive composition used in the present invention, the weight ratio of the alicyclic epoxy compound and the oxetane compound is (95 to 65) parts by weight (5 to 35) parts by weight, preferably (80 to 70) parts by weight. Parts by weight (20 to 30) parts by weight. If the monofunctional oxetane compound is too small, the liquid properties such as the viscosity and surface tension of the adhesive composition are not good, and conversely if the monofunctional oxetane compound is added too much, the cured product becomes too flexible and the adhesive strength. Decreases. The onium salt photoinitiator may be used in a catalytic amount, and the addition amount is 0.3 to 10 parts by weight with respect to 100 parts by weight of the total of the alicyclic epoxy compound and the oxetane compound. The preferred range is 5 parts by weight.

  In the present invention, the adhesive composition is inserted between the optical component and the fixing member so that the adhesive thickness is 0.05 μm or more and 5 μm or less. Below this adhesive thickness, the adhesive strength is insufficient, and above this thickness, the adhesive shrinkage tends to be adversely affected. An adhesion thickness of 0.05 μm or more and 2 μm or less is preferable, and an adhesion thickness of 0.2 μm or more and 1 μm or less is particularly preferable.

  In the present invention, it is preferable to further add a silane coupling agent to the adhesive composition. The silane coupling agent is considered to have a property of chemically bonding an optical component and an adherent inorganic member or metal member to the adhesive composition. By using this silane coupling agent in combination, the adhesive strength and the adhesive durability can be improved. As the silane coupling agent used in combination with the present invention, epoxy silanes having an epoxy group and a trimethoxysilyl group in one molecule are preferably used. Such a coupling agent is available from Shin-Etsu Chemical Co., Ltd. under trade names such as KBM303, KBM403, and KBE402. The preferred use range of the silane coupling agent is 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the total of the alicyclic epoxy compound and the oxetane compound.

  In the present invention, it is preferable that spherical particles are contained in the adhesive composition. The silica particles preferably have a diameter of 0.1 μm to 2 μm and have a particle size distribution as uniform as possible. Particles having an average particle size of 0.2 μm or more and 0.8 μm or less are preferably used in the present invention, and silica particles having a nearly spherical shape and few ionic impurities are particularly preferably used. The thermal durability of the cured adhesive composition can be improved by adding the silica particles. The addition amount of the spherical silica particles can be appropriately selected within the range of 1 to 20 parts by weight with respect to 100 parts by weight of the adhesive composition. Synthetic quartz spherical silica is commercially available from Tatsumori Co., Ltd.

  In the present invention, the adhesive composition is preferably used for adhesion between an inorganic transparent member such as a lens and a reflection mirror and a metal fixing member such as a metal (copper, copper alloy, aluminum, etc.) holder that adheres and fixes the same. The

  As a result of intensive studies, the inventor preferably adjusts the viscosity at room temperature (25 ° C.) of the adhesive composition to 10 mPa · s or more and 1,000 mPa · s or less, and the viscosity is 80 mPa · s or more and 300 mPa · s. It is further preferable to adjust to the following, and in addition, it is preferable that the contact angle between the adhesive composition and the adherend is 40 degrees or less, more preferably 30 degrees or less to provide good adhesive fixation. I found it. In order to adjust the composition viscosity, the addition of a monofunctional oxetane compound is effective. If necessary, the contact angle can be adjusted by adding a fluorosurfactant. Fluorosurfactants are surfactants having fluorocarbon as a hydrophobic group, and there are three types of anions, cations, and nonions. In the present invention, the use of fluorinated alkyl ester nonionic surfactants is possible. preferable. The addition amount of this nonionic surfactant is 0.1 to 1 part by weight with respect to 100 parts by weight of the adhesive composition. This nonionic surfactant is commercially available from Sumitomo 3M Co., Ltd. under the trade name of FLORARD (FC170C, 171 430, 431, etc.).

  In addition to the above additives, inert components such as dyes and pigments can be appropriately added to the adhesive composition used in the present invention. In addition, for the purpose of improving photocurability, a photosensitizer such as pyrene, perylene, acridine orange, thioxanthone, 2-chlorothioxanthone, and benzopyran may be added. Various light sources can be used as the ultraviolet light source for curing with ultraviolet rays, and examples thereof include mercury arc lamps, xenon arc lamps, carbon arc lamps, and tungsten-halogen copying lamps.

  According to the first laser module manufacturing method of the present invention, plasma is applied to at least the inside of the container and the semiconductor laser element before the container is hermetically sealed. Contaminants such as hydrocarbons and silicon compounds, as well as contaminants present in the atmosphere in the container can be satisfactorily decomposed and removed by plasma irradiation. Therefore, it is possible to obtain a highly reliable laser module from which contaminants are well removed. In addition, since the plasma irradiation can be performed by an existing semiconductor manufacturing apparatus such as a dry etching apparatus or a plasma stripping apparatus, it is not necessary to use a new apparatus and it is possible to remove contaminants with high accuracy by a simple method. It is.

  In addition, according to the second laser module manufacturing method of the present invention, as in the first laser module manufacturing method, the contaminants adhered to the container, the semiconductor laser element, the optical member, and the optical fiber can be improved by plasma. Can be removed. Since contaminants are likely to be deposited on the surface of the optical member and the input end of the optical fiber, it is effective to apply the present invention.

  In particular, in the case of a semiconductor laser device having an oscillation wavelength of 450 nm or less, the deposition rate and amount of contaminants by these short wavelength laser beams are larger than those in the case of long wavelength laser beams. It is effective.

  In the present invention, when the above-mentioned adhesive composition is used for bonding the optical component and the fixing member, the curing shrinkage rate (linear shrinkage rate) when the adhesive is cured can be suppressed to about 2%. Therefore, when an optical component such as a semiconductor laser element, a collimator lens, a condenser lens, or an optical fiber constituting the laser module is fixed to the fixing member with the adhesive composition, the layer thickness of the adhesive composition is 5 μm or less. If adjusted, even if curing shrinkage of the uncured portion of the adhesive composition proceeds, the shrinkage can be suppressed to an extremely low level of about 5 × 0.02 = 0.1 μm. Further, the above-mentioned adhesive composition penetrates uniformly even when the distance between the optical component and the fixing member is as narrow as about 1 μm, and generates a strong and flexible cured product even after curing with ultraviolet rays or the like. Therefore, adhesion without occurrence of peeling can be realized in a wide temperature range from low temperature (−25 ° C.) to high temperature (70 ° C.). As described above, since the relative positional accuracy of the optical component as described above is kept high, the laser module manufacturing method according to the present invention can provide a highly reliable laser module from this point.

  In the method for producing a laser module of the present invention, the adhesive composition has a viscosity at room temperature of 10 mPa · s to 1,000 mPa · s, and a contact angle with an adherend of 40 ° or less. When a material is used, as described above, particularly good adhesive fixation can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, the manufacturing method of the can type sealing laser module by the 1st Embodiment of this invention is demonstrated. FIG. 1 shows a schematic configuration diagram of the laser module. A schematic cross-sectional view of the plasma irradiation apparatus is shown in FIG.

As shown in FIG. 1, in this laser module, on a stem 1, a heat sink 4 in which a semiconductor laser element 6 is bonded to a submount 5, an electrode terminal 8 connected from the semiconductor laser element 6 by a wire 9, and a wire A monitoring photodiode 10 connected to the electrode terminal 11 by 12 is fixed. These elements are ring-welded in a dry air (N ₂ = 80%, O ₂ = 20%) atmosphere by a container 2 having a glass window 3 on which an antireflective coating is applied. The internal volume of the container 2 is 67.5 mm ³ .

  FIG. 1 does not describe the front half of the cylindrical container 2 in order to facilitate understanding of the component configuration in the container.

  In the laser module according to the present embodiment, laser light 7 which is forward emission light of the semiconductor laser element 6 is emitted from the window glass 3 coated with non-reflective coating, and the backward emission light of the semiconductor laser element 6 is emitted from the monitor photodiode. The amount of emitted light is sensed by 10 and the current is automatically controlled so that the output of the laser beam 7 is constant.

  Next, a method for manufacturing the laser module according to this embodiment will be described. First, on the stem 1, the heat sink 4 having the semiconductor laser element 6 bonded to the submount 5 and the photodiode 10 are fixed, connected from the semiconductor laser element 6 to the electrode terminal 8 by the wire 9, and further from the photodiode 10. Connect to the electrode terminal 11 with a wire 12.

Next, plasma irradiation is performed on the components on the stem 1. As shown in FIG. 2, the stem 1 on which each of the above components is fixed is set on the fixed base 65 in the vacuum chamber 60, and exhaust 63 is performed. After evacuating from the atmosphere until the initial degree of vacuum becomes 1 × 10 ⁻² Torr or less, about 62 to 1000 W by introducing microwave 62 and argon gas 61 of 1 × 10 ⁻² to 1 × 10 ⁻¹ Torr Is applied to generate plasma 64, and plasma irradiation is performed in about 60 minutes or less.

As the gas to be introduced, pollutants composed of hydrocarbons and organosilicon compounds can be sufficiently removed even with argon alone, but a gas such as nitrogen, oxygen, hydrogen, or chlorofluorocarbon should be appropriately mixed with argon gas. However, it is more desirable in order to decompose and remove the contaminants well. For example, when it is desired to positively remove hydrocarbons, a mixed gas of oxygen and argon is preferable. When it is desired to positively remove organic silicon compounds, a mixed gas of argon and chlorofluorocarbon, such as CF _4, is preferable. Note that the mixing ratio of each gas in the mixed gas is preferably adjusted as appropriate in consideration of the configuration of the laser module, irradiation conditions, and the like.

Thereafter, the stem 1 on which each component is installed is taken out from the plasma irradiation apparatus, and is placed in a dry air (N ₂ = 80%, O ₂ = 20%) atmosphere with a container 2 equipped with a window glass provided with an antireflection coating. , Ring weld sealed.

  In plasma irradiation, if the irradiation time is too long or the input power is too large, the damage by the plasma may be large. In such a case, the optical component or the like is physically or chemically etched, the surface of the optical component on the optical path is roughened, and an optical loss occurs. Such over-etching can be suppressed by adjusting the irradiation time or the input power so that the residue of etching gas such as argon physically adsorbed on the surface of the component becomes a certain amount or less.

  The reliability over time of the laser module of the present invention and the conventional laser module was evaluated. FIG. 3 shows changes in the drive current of the conventional laser module over time, and FIG. 4 shows changes in the drive current of the laser module of the present invention over time. The vertical axis of the graph is a value obtained by normalizing the drive current with the initial drive current.

As the laser module of the present invention, the laser module according to the first embodiment, in which the oscillation wavelength of the semiconductor laser element 6 is 405 nm, was used. The configuration of the laser module of the conventional example is the same as that of the above embodiment, and plasma irradiation is not performed. Both the conventional example and the sealing atmosphere in the laser module of the present invention are dry air (N ₂ = 80%, O ₂ = 20%). The drive conditions were evaluated by adjusting the drive current so that the optical output was 30 mW at an environmental temperature of 25 ° C.

  In the laser module of the conventional example, as shown in FIG. 3, a change in driving current is seen over time, but in the laser module of the present invention, as shown in FIG. 4, no increase in driving current is seen and stable over time. doing. From this, it can be confirmed that contaminants such as hydrocarbons and silicon compounds are well removed by plasma irradiation.

Next, adhesion of the semiconductor laser element 6 to the submount 5 which is a fixing member made of a metal such as copper will be described. The adhesive surface of the semiconductor laser element 6 was brought into close contact with the adhesive surface of the submount 5 and an adhesive composition described in detail below was inserted into the gap, and then cured by ultraviolet irradiation. Union Carbide Japan Co., Ltd. UVR6128 (bis (3,4-epoxycyclohexyl) adipate) was used as the alicyclic epoxy compound, and Aron Oxetane OXT-212 (EHOX) from Toa Gosei Co., Ltd. was used as the monofunctional oxetane compound. And UVI-6990 (PF5 salt of triarylsulfonium) manufactured by Union Carbide Japan Co., Ltd. was used as a photoinitiator, and the weight ratio of these components was set as shown in Table 1 below. Then, adhesive composition Examples 1 to 3 and Comparative Example 1 were prepared.

  After the adhesive composition was cured by UV irradiation, the adhesion uniformity was visually observed with an optical microscope. The adhesives of Examples 1 to 3 combined with the oxetane compound EHOX were compared with the adhesive of Comparative Example 1 that was not used in combination. Also showed excellent uniformity of the adhesive surface.

  Next, a laser module according to the second embodiment of the present invention will be described. FIG. 5 shows a schematic side view and a plan view of the laser module.

In the laser module according to the present embodiment, as shown in FIG. 5A, a base plate 42 is fixed to the bottom surface of the container 40, and seven GaN-based semiconductor laser elements LD21 are formed on the base plate 42. Heat block 20 to which LD27 is bonded, collimator lenses 31 to 37 held by collimator lens holder 44 attached to heat block 20, condensing lens 43 held by condensing lens holder 45, and fiber A multimode optical fiber 30 held by a holder 46 is fixed. An opening is formed in the wall surface of the container 40, and a wiring 47 for supplying a driving current to the GaN-based semiconductor laser elements LD21 to LD27 is drawn out of the container through the opening. The internal volume of the container 40 is about 8160 mm ³ .

  Further, as shown in FIG. 5B, each of the collimator lenses 31 to 37 is formed in a shape obtained by cutting an area including the optical axis of a circular lens having an aspherical surface into an elongated shape on a parallel plane. This elongated collimator lens can be formed, for example, by molding resin or optical glass. The collimator lenses 31 to 37 are closely arranged in the arrangement direction of the light emitting points so that the length direction is orthogonal to the arrangement direction of the light emitting points of the GaN-based semiconductor laser elements LD21 to LD27.

  In FIG. 5, in order to avoid complication of the drawing, only the semiconductor laser elements LD21 and LD27 are denoted by reference numerals among the plurality of GaN-based semiconductor laser elements, and the collimator lenses 31 and 37 among the plurality of collimator lenses are provided. Only the code | symbol is attached | subjected.

  On the other hand, each of the GaN-based semiconductor laser elements LD21 to LD27 includes an active layer having an emission width of 2 μm, and each laser has a divergence angle of 10 ° or 30 ° in a direction parallel to or perpendicular to the active layer, respectively. A laser that emits beams B21 to B27 is used. These semiconductor laser elements LD21 to LD27 are arranged so that the light emitting points are aligned in a direction parallel to the active layer.

Therefore, in the laser beams B21 to B27 emitted from the respective light emitting points, the direction in which the divergence angle is large matches the length direction with respect to the elongated collimator lenses 31 to 37 as described above, and the direction in which the divergence angle is small. Is incident in a state that coincides with the width direction (direction orthogonal to the length direction). That is, each of the collimator lenses 31 to 37 has a width of 1.1 mm and a length of 4.6 mm, and each of the laser beams B21 to B27 incident thereon has a focal length f ₁ = 3 mm, NA = 0.6, Lens arrangement pitch = 1.25 mm.

The condensing lens 43 is a shape in which a region including the optical axis of a circular lens having an aspheric surface is cut out in a parallel plane and is long in the arrangement direction of the collimator lenses 31 to 37, that is, in the horizontal direction and short in the direction perpendicular thereto. Is formed. The condenser lens 43 has a focal length f ₂ = 12.5 mm and NA = 0.3. This condensing lens 43 is also formed by molding resin or optical glass, for example.

  The multimode optical fiber 30 may be any of a step index type optical fiber, a graded index type optical fiber, and a composite type optical fiber. For example, a graded index optical fiber manufactured by Mitsubishi Cable Industries, Ltd. can be used. This optical fiber has a graded index at the center of the core and a step index at the outer periphery, the core diameter = 25 μm, NA = 0.3, and the transmittance of the end coat = 99.5% or more.

  In the laser module according to the present embodiment, each of the laser beams B21, B22, B23, B24, B25, B26 and B27 emitted in a divergent light state from each of the GaN-based semiconductor laser elements LD21 to LD27 constituting the combined laser light source Are collimated by the corresponding collimator lenses 31-37. The collimated laser beams B21 to B27 are collected by a condenser lens and converge on the incident end face of the multimode optical fiber 30.

  In this embodiment, a condensing optical system is configured by the collimator lenses 31 to 37 and the condensing lens. The condensing optical system and the multimode optical fiber 30 enter the optical fiber and propagate through the optical fiber. It is combined with the beam and emitted from the multimode optical fiber.

  In the laser module, the coupling efficiency of the laser beams B21 to B27 to the multimode optical fiber is 0.9. Therefore, when the outputs of the GaN-based semiconductor laser elements LD21 to LD27 are 100 mW, a combined laser beam with an output of 630 mW (= 100 mW × 0.9 × 7) can be obtained.

Next, a method for manufacturing the laser module according to this embodiment will be described. First, as shown in FIG. 5, a base plate 42 is fixed to the bottom surface of the container 40, and a heat block 20 in which seven GaN-based semiconductor laser elements LD21 to LD27 are bonded on the base plate 42, and the heat block The collimator lenses 31 to 37 held by the collimator lens holder 44 attached to 20, the condenser lens 43 held by the condenser lens holder 45, and the multimode optical fiber 30 held by the fiber holder 46 are fixed. Set up. Next, as in the first embodiment, in the plasma irradiation apparatus shown in FIG. 2, the container 40 in which the above components are fixed is set on the fixed base 65 in the vacuum chamber 60, and exhaust 63 is performed. . After evacuating from the atmosphere until the initial degree of vacuum becomes 1 × 10 ⁻² Torr or less, about 62 to 1000 W by introducing microwave 62 and argon gas 61 of 1 × 10 ⁻² to 1 × 10 ⁻¹ Torr Is applied to generate plasma 64, and plasma irradiation is performed in about 60 minutes or less.

  Further, in the laser module shown in FIG. 5, in order to remove an outgas component (organic gas or the like) from the adhesive, after performing a deaeration process described in Japanese Patent Application No. 2002-101714 at 90 ° C. for 192 hours, Even when the plasma treatment according to the present invention was performed, high reliability over time could be obtained as described above.

Next, adhesion of the collimator lenses 31 to 37 to the collimator lens holder 44 which is a fixing member made of metal such as copper will be described. The adhesive surface of the collimator lenses 31 to 37 (the lower end surface in FIG. 5B) is brought into close contact with the adhesive surface of the collimator lens holder 44, and an adhesive composition described in detail below is inserted into the gap, followed by ultraviolet rays. Cured by irradiation. Union Carbide Nippon Co., Ltd. UVR6128 is used as the alicyclic epoxy compound, and bisphenol F-type Epicoat 806 manufactured by Yuka Shell Epoxy Co., Ltd. is used as the bifunctional glycidyl compound, and the monofunctional oxetane compound as Toa. Aron Oxetane OXT-212 (EHOX) of Synthetic Co., Ltd. is used in combination as necessary, and UVI-6990 (PF5 salt of triarylsulfonium) manufactured by Union Carbide Japan Co., Ltd. is used as a photoinitiator. As a silane coupling agent, KBE303 manufactured by Shin-Etsu Chemical Co., Ltd. and synthetic quartz spherical silica 1-FX (average particle size 0.38 μm) manufactured by Tatsumori Co., Ltd. are used in combination as necessary. The weight ratio was set as shown in Table 2 below, and adhesive composition examples 4 to 10 were prepared.

  After the adhesive composition was cured by ultraviolet irradiation and subjected to a storage test at −25 ° C. to 70 ° C., the peel occurrence rate of the adhesive surface was measured, and the results shown in Table 2 were obtained. Examples 5 and 6 using an adhesive composition with an increased amount of the monofunctional oxetane compound EHOX show lower peeling rates than Example 4, and further Examples 7 and 6 using an adhesive combined with a silane coupling agent No. 8 was further reduced in the occurrence rate of peeling, and no peeling was observed particularly in Example 8. Example 9 is an embodiment in which a bisphenol F-type diglycidyl compound is optionally used in combination with an alicyclic epoxy compound, and Example 10 is an embodiment in which synthetic quartz spherical silica is optionally added. However, in any case, no peeling occurred between the collimator lens holder 44 and the adhesive layer even in the forced storage test.

  Further, after the adhesive composition was cured by irradiating ultraviolet rays, the layer thickness of each adhesive between the collimator lens holder 44 and the collimator lenses 31 to 37 was measured. It was 6 μm. This adhesive had a volume hardening shrinkage of 4 to 5%, and the thickness change of each adhesive layer after a storage test at -25 ° C to 70 ° C was suppressed to 0.03 µm or less. Therefore, the relative positional relationship between the GaN-based semiconductor laser elements LD21 to LD27 and the collimator lenses 31 to 37 whose optical axes have been adjusted does not go out of alignment due to the adhesion, and a good multiplexing effect can be obtained.

  Note that the bonding method as described above includes bonding between the other optical components in the container 40 and the fixing member, for example, bonding between the condensing lens 43 and the condensing lens holder 45, and the multimode optical fiber 30 and the fiber holder 46. In this case, the same effects as described above are basically obtained.

  Furthermore, the bonding method as described above is not limited to the laser modules shown as the first and second embodiments, but generally includes optical components such as a light source, a lens, a mirror, a half mirror, a concave mirror, a convex mirror, and a diffraction grating. In the laser module, the present invention can be widely applied to bonding and fixing these optical components and their fixing members, and even in such a case, the same effects as described above are basically obtained.

  In the first and second embodiments, the plasma irradiation is performed after the semiconductor laser element and other parts are installed. However, in the state of the parts before the installation, these are installed on the fixed base and the plasma is applied. Irradiation may be performed. In addition, plasma irradiation may be performed in the state of a part, and plasma irradiation may be performed after being installed in a container.

  In the laser module manufacturing method of the present invention, after plasma irradiation, argon, oxygen, or chlorofluorocarbon gas contained in the plasma atmosphere may remain in the container, but none of these can cause contamination. It does not degrade the laser characteristics.

  According to the present invention, it is possible to satisfactorily remove contaminants such as hydrocarbon compounds and silicon compounds present in a container in which a semiconductor laser element is sealed, so that a highly reliable laser module is provided. be able to.

1 is a schematic configuration diagram showing a laser module according to a first embodiment of the present invention. Schematic showing the plasma irradiation device Graph showing the change over time of drive current in a laser module according to the conventional method The graph which shows the time-dependent change of the drive current in the laser module by the 1st Embodiment of this invention. The schematic block diagram which shows the laser module by the 2nd Embodiment of this invention.

Explanation of symbols

1 Stem 2 Lid 3 Window Glass 4 Heat Sink 5 Submount 6 Semiconductor Laser Element 7 Laser Light 8, 11 Electrode Terminal 9, 12 Wire
10 Monitor photodiode
30 Multimode optical fiber
31-37 Collimator lens
40 containers
43 condenser lens
44 Collimator lens holder
45 Condenser lens holder
LD21 to LD27 GaN-based semiconductor laser device

Claims (9)

A method for manufacturing a laser module, wherein a semiconductor laser element is installed in a container and hermetically sealed,
An alicyclic epoxy compound having an epoxy group, a compound having an oxetanyl group, and a catalytic amount of an onium salt photoinitiator are contained between at least one optical component in the container and a fixing member for fixing the optical component. After inserting the adhesive composition to be fixed, the optical component is fixed to the fixing member by curing with an active energy ray,
A method of manufacturing a laser module, comprising: irradiating at least the inside of the container and the semiconductor laser element with plasma before hermetically sealing the container. A method of manufacturing a laser module in which a semiconductor laser element, an optical fiber, and an optical member for inputting laser light emitted from the semiconductor laser element into an optical fiber are installed in a container and hermetically sealed. And
An alicyclic epoxy compound having an epoxy group, a compound having an oxetanyl group, and a catalytic amount of an onium salt photoinitiator are contained between at least one optical component in the container and a fixing member for fixing the optical component. After inserting the adhesive composition to be fixed, the optical component is fixed to the fixing member by curing with an active energy ray,
A method for manufacturing a laser module, comprising: irradiating at least the inside of the container, a semiconductor laser element, an optical fiber, and an optical member with plasma before the container is hermetically sealed.   3. The method of manufacturing a laser module according to claim 1, wherein the gas sealed in the container is at least one of an inert gas, nitrogen, and oxygen.   4. The method of manufacturing a laser module according to claim 3, wherein an oscillation wavelength of the semiconductor laser element is 450 nm or less.   The method for producing a laser module according to claim 1, wherein the adhesive composition contains a silane coupling agent.   The method for manufacturing a laser module according to any one of claims 1 to 5, wherein the adhesive composition contains spherical silica particles having an average diameter of 0.1 µm or more and 1.0 µm or less.   The method for manufacturing a laser module according to claim 1, wherein the fixing member is made of a metal member, and the optical component is made of an inorganic transparent member. The method for producing a laser module according to any one of claims 1 to 7, wherein the compound having an oxetanyl group is represented by the following general formula (1).

In the formula (1), R ₁ represents a methyl group or an ethyl group, and R ₂ represents a hydrocarbon group having 6 to 12 carbon atoms.   9. The adhesive composition according to claim 1, wherein the adhesive composition has a viscosity at room temperature of 10 mPa · s to 1,000 mPa · s and a contact angle with an adherend of 40 ° or less. 2. A method for manufacturing a laser module according to item 1.

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